Ghisellini 2008 Swift余辉的统一模型

主要内容:
由于Swift早期余辉的复杂性, 现在还没有统一的模型. 文章将余辉分为两部分, 一是传统的和外部介质相互作用的余辉, 加上唯象的flares, 而原因待定.

精彩摘抄:
左边是prompt晚期, 中间是余辉, 右边是二者加起来. 这里没加上flares.


文章信息:

· arXiv e-print (arXiv:0811.1038)

· References in the Article

·

· Translate This Page

Title:		A unifying view of Gamma Ray Burst Afterglows
Authors:		Ghisellini, G.; Nardini, M.; Ghirlanda, G.; Celotti, A.
Publication:		eprint arXiv:0811.1038
Publication Date:		11/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		20 pages, 17 figures, Accepted for publication in MNRAS
Bibliographic Code:		2008arXiv0811.1038G

Abstract

We selected a sample of 33 Gamma Ray Bursts (GRBs) detected by Swift, with known redshift and optical extinction at the host frame. For these, we constructed the de-absorbed and K-corrected X-ray and optical rest frame light curves. These are modelled as the sum of two components: emission from the forward shock due to the interaction of a fireball with the circum-burst medium and an additional component, treated in a completely phenomenological way. The latter can be identified, among other possibilities, as "late prompt" emission produced by a long lived central engine with mechanisms similar to those responsible for the production of the "standard" early prompt radiation. Apart from flares or re-brightenings, that we do not model, we find a good agreement with the data, despite of their complexity and diversity. Although based in part on a phenomenological model with a relatively large number of free parameters, we believe that our findings are a first step towards the construction of a more physical scenario. Our approach allows us to interpret the behaviour of the optical and X-ray afterglows in a coherent way, by a relatively simple scenario. Within this context it is possible to explain why sometimes no jet break is observed; why, even if a jet break is observed, it is often chromatic; why the steepening after the jet break time is often shallower than predicted. Finally, the decay slope of the late prompt emission after the shallow phase is found to be remarkably similar to the time profile expected by the accretion rate of fall-back material (i.e. proportional to t^{-5/3}), suggesting that this can be the reason why the central engine can be active for a long time.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)